Finland and Sweden will be able to join NATO quickly should they decide to ask for membership in the Western military alliance, NATO Secretary-General Jens Stoltenberg said on Thursday, ABC News reported.

"If they decide to apply, Finland and Sweden will be warmly welcomed and I expect the process to go quickly," Stoltenberg told reporters in Brussels, adding he planned to speak with the Finnish president later in the day.

He expressed confidence that mechanisms could be found for an interim period between the two Nordic countries' application and formal ratification in the parliaments of all 30 NATO members.

"I am confident that there are ways to bridge that interim period in a way which is good enough and works for both Finland and Sweden," Stoltenberg said.

Public support for NATO membership in the two Scandinavian countries has been growing since the start of the Russia-Ukraine conflict. A March poll by Finnish broadcaster YLE showed that, for the first time, more than 50 percent of Finns supported joining the Western military alliance.

In neighboring Sweden, a similar poll showed that the number of supporters of joining NATO exceeded the number of opponents.